This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 2000-049842, filed Feb. 25, 2000; and Japanese Patent Application No. 2000-207443, filed Jul. 7, 2000, the entire contents of which are incorporated herein by reference.
The present invention relates to a totally enclosed type driving electric motor which is used, for example, in a railway vehicle (particularly, an electric railcar) or the like.
A driving electric motor for a railway vehicle is ventilated and cooled so as to prevent a temperature at a driving time from being increased over a preset value. That is, in the driving electric motor, a cooling wind is taken into an internal portion from an external portion so as to prevent an abnormality in a function of an insulating material and each of members from being generated due to a heat generated by energizing at a time of using the motor, and each of the members within the motor is cooled.
In the general motor, an open air is taken into the motor in accordance with a rotation of a ventilation fan attached to a rotary shaft within the motor. The sucked open air flows through the inner portion of the motor. Accordingly, a heat generating portion is ventilated and cooled.
However, when the open air is taken into the motor so as to perform a cooling operation, dusts contained in the open air are attached to the inner portion of the motor. Accordingly, the inner portion of the driving electric motor is spoiled. In the driving electric motor soiled in the inner portion, a heat radiating efficiency is reduced and a function of the motor is reduced. Therefore, it is necessary to dissemble the driving electric motor at a fixed period so as to take care thereof such as cleaning or the like. Since a lot of labor is required for the cleaning operation, it is required to improve in view of maintenance.
Further, a sound generated by rotation of a ventilating fan for communicating the open air is leaked to an external portion from a port through which the air blows to the external portion from the inner portion of the driving electric motor. The rotation sound of the ventilating fan becomes a large sound in an area having a great number of rotation (in a high speed operation area). Accordingly, it is required to improve the sound.
In order to improve the problems, development of a totally enclosed type driving electric motor has been promoted in recent years. Since the totally enclosed type driving electric motor does not flow the open air into the motor, the inner portion of the motor is not spoiled for a long period. Accordingly, the totally enclosed type driving electric motor is not required to be dissembled, and it is possible to save a maintenance.
Further, since the totally enclosed type driving electric motor does not require a ventilating fan, it is possible to avoid the sound generated by the rotation of the fan, and it is possible to achieve a widely low sound.
FIG. 18 is a cross sectional view showing a first embodiment of a structure of a conventional totally enclosed type driving electric motor. FIG. 18 shows a state in which a rotary axis of a shaft provided in the totally enclosed type driving electric motor is horizontal. FIG. 18 shows an upper half portion of the totally enclosed type driving electric motor in a side cross section parallel to the rotary axis of the shaft, and omits a lower half portion substantially symmetrical to the rotary axis of the shaft.
The conventional totally enclosed type driving electric motor 1 is provided with a frame 2 formed in a cylindrical shape. A cylindrical stator core 3 is mounted to an inner peripheral surface (interior surface) of the frame 2.
A multiplicity of grooves are formed on an inner peripheral surface of the stator core 3 in an axial direction. A stator coil 4 is mounted to the grooves.
A bearing bracket 6 supporting a bearing 5 is provided in one end portion of the frame 2.
A housing 8 supporting a bearing 7 is provided in the other end portion of the frame 2.
The bearing 5 and the bearing 7 rotatably support a shaft 9 of a rotor. The shaft 9 is coaxially provided with the stator core 3.
Further, a lubricating agent such as a lubricating grease or the like for smoothening a rotational operation of the shaft 9 is charged in the bearing 5 and the bearing 7.
A rotor core 10 is provided in a center portion of the shaft 9. A rotor 11 is mounted to a multiplicity of grooves formed on an outer peripheral surface (outer surface) of the rotor core 10.
A rotating force generated in the rotor core 10 is transmitted to a drive apparatus by an end portion 9a of the shaft 9.
A multiplicity of cooling fins 2a and 2b are provided on the outer peripheral surface of the frame 2 and a side surface of the other end portion of the frame 2. The cooling fins 2a and 2b radiate heat generated within the motor to the open air. Further, a multiplicity of cooling fins 6a are also provided on a side surface of the bearing bracket 6.
FIG. 19 is an outer appearance view showing a mounting state of the conventional totally enclosed type driving electric motor 1 structured in the manner mentioned above. FIG. 19 is a view obtained by seeing the totally enclosed type driving electric motor 1 from a direction of the rotary axis of the shaft 9 provided in the totally enclosed type driving electric motor 1 and from a side of the bearing bracket 6.
The totally enclosed type driving electric motor 1 is fixed and supported to a truck frame 12 by supporting arms 2c and 2d provided in a part of the frame 2.
A drive apparatus constituted by a gear (a large gear) 13, a pinion (a small gear) 14 and a gear box 15 is provided in adjacent to the totally enclosed type driving electric motor 1.
A rotating force of the totally enclosed type driving electric motor 1 is transmitted to the pinion 14 by an end portion 9a of the shaft 9, and rotates an axle 16a of a tire wheel 16 through the gear 13 meshed with the pinion 14. Accordingly, a vehicle 17 runs on rails 18.
In the totally enclosed type driving electric motor 1, the heat generated in the stator coil 4 and a rotor bar 11 corresponding to a heat generating portion is discharged to the open air from the frame 2 and the shaft 9 via the stator core 3 and the rotor core 10. Further, in the totally enclosed type driving electric motor 1, the air within the motor is heated by the heat generated in the stator coil 4 and the rotor bar 11. Further, the heat of the air within the motor is transmitted to the frame 2, the bearing bracket 6 and the housing 8 and radiated to the open air. Accordingly, in the conventional totally enclosed type driving electric motor 1, the whole of the apparatus becomes in a heated state.
On the other hand, since a self-ventilation cooling motor is structured such that a cooling wind directly flows through the heat generating portion, the heat in the heat generating portion is discharged to the external portion by the cooling wind at a high rate, so that a temperature of the other portions than the heat generating portions such as the frame, the bearing bracket, the shaft and the like are hard to be increased.
Accordingly, in the conventional totally enclosed type driving electric motor 1, the temperature of the bearing bracket 6, the housing 8, the shaft 9 and the like are widely increased due to the heat within the motor in comparison with the self-ventilation type cooling driving electric motor. Therefore, in the conventional totally enclosed type driving electric motor 1, a lubricating grease is quickly deteriorated due to the heat and the lubricating service life becomes short, so that it is necessary to early replace the grease.
The totally enclosed type driving electric motor 1 is structured such as to save the maintenance by preventing the inner portion of the motor from being spoiled so as to extend a period between the dissembling operations. However, it is a problem that the dissembling operation should be early performed for replacing the lubricating grease of the bearings 5 and 7 as mentioned above.
A description will be given below of another totally enclosed type driving electric motor.
FIG. 20 is a cross sectional view showing a second embodiment of a structure of a conventional totally enclosed type driving electric motor. FIG. 20 is shown in the same state as that of FIG. 18. Further, the same reference numerals are attached to the same elements shown in FIG. 20 as the elements shown in FIG. 18.
The stator core 3 is fitted to the inner peripheral portion of the cylindrical frame 2 provided in a totally enclosed type driving electric motor 19. A multiplicity of grooves are formed in the inner peripheral portion of the stator core 3 in an axial direction. The stator coil 4 is mounted to the grooves.
A bearing bracket (mirror cover) 20 supporting the bearing 5 is provided in one end portion of the frame 2.
The bearing 5 supports the shaft 9 of the rotor. The bearing 5 rotatably supports the rotor. The bearing 5 is formed in a cylindrical shape and the shaft 9 passes through the inner diameter portion.
A side plate 2e is formed in another end portion of the frame 2. Further, the housing 8 supporting the bearing 7 is provided in an inner peripheral portion of the side plate 2e. 
A lubricating grease 21 is charged in the bearings 5 and 7 and a periphery thereof. The bearings 5 and 7 are lubricated by the lubricating grease 21. The bearing bracket 20 and an end cover 22 charging the lubricating grease 21 support an outer wheel 5a of the bearing 5 in a fixing state.
In the same manner, the housing 8 and an end cover 23 charging the lubricating grease 21 support an outer wheel 7a of the bearing 7 in a fixing state.
Rotating bodies 5b and 7b are arranged in the bearings 5 and 7 in such a manner as to be in inward contact with the outer wheels 5a and 7a. Inner wheels 5c and 7c of the bearings 5 and 7 are arranged in a state of being in outward contact with the rotating bodies 5b and 7b. Inner peripheral surfaces of the inner wheels 5c and 7c and the shaft 9 are fitted and attached to each other.
Collars 24 to 26 are formed in a cylindrical shape. The shaft 9 passes through inner diameter portions of the collars 24 to 26. The collars 24 to 26 are fitted and attached to the outer peripheral surface of the shaft 9. The collar 24 is arranged so that an outer peripheral surface opposes to the end cover 22. The collar 25 is arranged so that an outer peripheral surface opposes to the bearing bracket 20. The collar 26 is arranged so that an outer peripheral surface opposes to the housing 8.
That is, the inner wheels 5c and 7c and the collars 24 to 26 rotate together with the shaft.
The rotor core 10 is provided in a center portion of the shaft 9. The rotor bar 11 is mounted to a multiplicity of grooves formed on the outer peripheral portion of the rotor core 10. End rings 27a and 27b are connected to both end portions of the rotor bar 11.
A multiplicity of cooling fins 28 for radiating the heat to the open air are provided in an outer portion of the frame 2, the side plate 2e and the bearing bracket 20. The cooling fin 28 efficiently radiates the heat generated from the stator coil 4 or the like.
Further, a fan 29 is mounted to the shaft 9. The structure is made such that the heat within the motor can be exchanged to the open air by a circulating duct 30 in accordance with rotation of the fan 29.
Further, a gear-shaped pressing plate 31 is mounted to the end portion of the shaft 9 in a side of the housing 8. The pressing plate 31 is provided with a cylindrical portion coaxially fitted and attached to the shaft 9 and a gear portion rotating with the same axis as that of the shaft 9.
Then, a sensor 32 for magnetically counting the gears in the pressing plate 31 is mounted to the totally enclosed type driving electric motor 19 so as to oppose to the gear portion of the pressing plate 31.
The pressing plate 31 and a magnetic sensing portion 32a in the sensor 32 are shut from the open air by a sensor case 33 and are protected from the external dusts.
A rotating force generated in the rotor is transmitted to the tire wheel via the drive apparatus from the end portion 9a in a drive side of the shaft 9.
In this conventional totally enclosed type driving electric motor 19, an efficiency of the heat radiation is intended by the cooling fin 28, however, a cooling performance is less than the motor introducing the cooling wind to the inner portion of the motor. Further, since the cooling performance of the totally enclosed type driving electric motor 19 is not sufficient, the lubricating grease 21 is deteriorated due to the heat, and the lubricating service life becomes short, so that it is necessary to early replace the grease and a lot of maintenance labor is required.
Accordingly, it becomes a problem on design how the cooling performance of the totally enclosed type driving electric motors 1 and 19 should be improved.
An object of the present Invention is to provide a totally enclosed type driving electric motor which can restrict a temperature increase of a bearing portion rotatably supporting a shaft, can prevent an early deterioration of a lubricating grease and can extend a period between dissembling operations for maintenance.
A first aspect relates to a totally enclosed type driving electric motor, comprising: a shaft; a frame which has the same axis as that of the shaft; a bearing bracket attached to one end of the frame in an axial direction; a housing attached to another end of the frame; a bearing which rotatably supports the shaft on a sides of said one end of the frame; a bearing support which is located outside a space defined by the frame, the bearing bracket, and the housing, and which supports the bearing; and a rib which couples the bearing bracket to the bearing support, wherein the bearing support is separated from the bearing bracket by the rib and a cooling space communicated with outside air.
In accordance with the first aspect, it is possible to prevent heat generated in the totally enclosed type driving electric motor from being transmitted to the bearing portion. Accordingly, it is possible to restrict a temperature increase of the bearing portion, prevent an early deterioration of a lubricating grease, and extend a non-dissembled period and it is possible to save a maintenance.
In general, in the totally enclosed type driving electric motor, a temperature of the outer wail portion such as the frame, the bearing bracket, the housing and the like becomes high.
However, in the first aspect, the cooling space is provided between the outer wall portion and the portion supporting the bearing.
Accordingly, even when the heat generated from the inner portion of the totally enclosed type driving electric motor is transmitted to the outer wall portion, it is possible to prevent the heat from being transmitted to the portion supporting the bearing at a front thereof. Therefore, in addition to the effect obtained by the structure of the totally enclosed type motor, it is possible to prevent the temperature increase of the bearing portion.
In the first aspect, the cooling space is formed in an annular (cylindrical) shape having the same axis as that of the shaft.
In the first aspect, it is possible to prevent the heat from being transmitted from all the directions toward the portion supporting the bearing from the bearing bracket and the housing. Further, it is possible to radiate the heat transmitted to the portion supporting the bearing from the shaft.
A second aspect is a totally enclosed type driving electric motor of the same type as that of the first aspect mentioned above. In this second aspect, the rib is provided with a cooling fin.
It is possible to further improve the cooling effect by providing the cooling fin in the rib, as in the second aspect.
A third aspect to further improve the cooling effect by providing the cooling fin in the rib, as in the second aspect.
A third aspect is a totally enclosed type driving electric motor of the same type as that of the first aspect mentioned above. In this third aspect, a collar is located between the bearing bracket and the shaft, a space between the bearing support and the collar forms a first labyrinth, and a space between the bearing bracket and the collar forms a second labyrinth.
A fourth aspect is a totally enclosed type driving electric motor of the same type as that of the first aspect mentioned above. In this fourth aspect, a collar is located on a surface of the shaft, a space between the bearing support and the collar forms a first labyrinth, a cap is located between the bearing bracket and the collar, and a space between the collar and the cap forms a second labyrinth.
In this fourth aspect, even if that the water or the like enters the cooling space together with the open air, it is possible to prevent the water or the like from entering the motor via the labyrinth by a groove. Accordingly, it is possible to extend the non-dissembled period and it is possible to save the maintenance.
In the fourth aspect, since the totally enclosed type driving electric motor can be constructed by machining the portion near the groove and thereafter assembling each of the portions, it is possible to easily machine the totally enclosed type driving electric motor.
A fifth aspect is a totally enclosed type driving electric motor of the same type as that of the first aspect. In this fifth aspect, a guide wind path which guides outside air from the outside into the cooling space between the bearing bracket and the bearing support is provided.
In this fifth aspect, since the open air is positively guided to the cooling space by the guide wind path, it is possible further improve the cooling effect.
A sixth aspect is a totally enclosed type driving electric motor, comprising: a shaft; a frame which has the same axis as that of the shaft, which is formed in a cylindrical shape, and which surrounds the shaft: a bearing bracket attached to one end of the frame in an axial direction; a housing attached to another end of the frame; a bearing which rotatably supports the shaft on a side of said another end of the frame; a bearing support which is located outside a space defined by the frame, the bearing bracket, and the housing, and which supports the bearing; and a rib which couples the housing to the bearing support, wherein the bearing support is separated from the housing by the rib and a cooling space communicated with outside air.
A seventh aspect is a totally enclosed type driving electric motor of the same type as that of the sixth aspect. In this seventh aspect, the rib is provided with a cooling fin.
An eighth aspect is a totally enclosed type driving electric motor of the same type as that of the sixth aspect. In this eighth aspect, a collar is located between said housing and the, shaft, a space between the bearing support and said collar forms a first labyrinth, and a space between said housing and the collar forms a second labyrinth.
A ninth aspect is a totally enclosed type driving electric motor of the same type as that of the sixth aspect. In this ninth aspect, a collar is located on a surface of the shaft, a space between the bearing support and the collar forms a first labyrinth, a cap is located between said housing and the collar, a space between the collar and the cap forms a second labyrinth, a groove is formed in the bearing support near the first labyrinth, and a groove is formed in the cap near the second labyrinth.
A tenth aspect is a totally enclosed type driving electric motor of the same type as that of the sixth aspect. In this tenth aspect, a guide wind path which guides outside air from the outside into the cooling space between the housing and the bearing is provided.
The sixth to tenth aspects mentioned above correspond to the aspects obtained by applying the structures of the bearing bracket side of the first to fifth aspects mentioned above to the structure of the housing. Accordingly, the sixth to tenth aspects can obtain the same effects due to the same operations as those of the first to fifth aspects.
An eleventh aspect is a totally enclosed type driving electric motor, comprising: a shaft; a frame which has the same axis as that of the shaft, which is formed in a cylindrical shape, and which surrounds the shaft a bearing bracket attached to one end of the frame in an axial direction; a housing attached to another end of the frame; a bearing which is supported by the bearing bracket and which rotatably supports the shaft; a collar which is located on a surface of the shaft, outside a space defined by the frame, the bearing bracket, and the housing, which is in contact with the bearing; and a fan which is connected to the collar, which rotates in accordance with a rotation of the collar, and which radiates heat transmitted from the bearing through the collar to outside air.
In the eleventh aspect, the fan is provided in a portion being in contact with the open air of the collar which is arranged near the bearing and rotates on the basis of the rotation of the shaft.
In this eleventh aspect, it is possible to prevent the heat generated in the inner portion of the totally enclosed type driving electric motor from being transmitted to the bearing portion via the various kinds of constituting members, whereby the temperature of the bearing is increased. Further, it is possible to prevent the air within the totally enclosed type driving electric motor from being heated, whereby the temperature of the bearing is increased.
Accordingly, it is possible to improve a cooling performance of the bearing portion and it is possible to restrict a temperature increase of the totally enclosed type driving electric motor. In particular, it is possible to prevent the lubricating grease from being early deteriorated so as to extend a non-dissembled period, and it is possible to provide an effective structure of the bearing portion in the totally enclosed type driving electric motor which can save on maintenance.
As mentioned above, since the fan is provided in the collar, it is possible to generate the cooling wand due to the rotation of the fan, and it is possible to radiate the heat from the fan, so that it is possible to realize a further effective cooling operation of the totally enclosed type driving electric motor.
A twelfth aspect is totally a enclosed type driving electric motor of the same type as that of the eleventh aspect. In this twelfth aspect, the fan generates a wind by rotating in accordance with the rotation of the collar, and the wind cools a part of the bearing bracket near the bearing.
As mentioned above, a further effective cooling operation of the totally enclosed type driving electric motor can be realized by bringing the wind generated due to the rotation of the fan into contact with a part of the bearing bracket near the bearing.
A thirteenth aspect is a totally enclosed type driving electric motor of the same type as that of the eleventh aspect mentioned above. In this thirteenth aspect, a cooling fin is connected to a part of the bearing bracket that receives wind.
As mentioned above, a further effective cooling operation of the totally enclosed type driving electric motor can be realized by providing the fin in the portion receiving the wind.
A fourteenth aspect is a totally enclosed type driving electric motor of the same type as that of the eleventh aspect mentioned above. In this fourteenth aspect, the fan is a disc portion concentric with the shaft, and a groove is formed in the surface of the disc portion.
As mentioned above, by forming the portion being in contact with the open air in the collar in a disc shape, it is possible to expand the area of the portion being in contact with the open air. Further, by providing the groove on the circular surface of the disc-like portion, it is possible to expand the area of the portion being in contact with the open air.
Accordingly, it is possible to realize a further effective cooling operation of the totally enclosed type driving electric, motor, and in particular, it is possible to effectively cool the portion near the bearing.
A fifteenth aspect is a totally enclosed type driving electric motor, comprising: a shaft; a frame which has the same axis as that of the shaft, which is formed in a cylindrical shape, and which surrounds the shaft a bearing bracket attached to one end of the frame in an axial direction: a housing attached to another end of the frame; a bearing which is supported by the housing and which rotatably supports the shaft; a pressing plate which is connected to the shaft, outside a space defined by the frame, the bearing bracket, and the housing, and which is in contact with the bearing; and a fan which is connected to a pressing plate, which rotates in accordance with a rotation of the pressing plate, and which radiates heat transmitted from the bearing through the pressing plate to outside air.
In this fifteenth aspect, the fan is connected to a portion in contact with the open air of the pressing plate which is arranged near the bearing and rotates based on the rotation of the shaft.
In this fifteenth aspect, it is possible to prevent the heat generated in the inner portion of the totally enclosed type driving electric motor from being transmitted to the bearing portion via the various kinds of constituting members, whereby the temperature of the bearing is increased. Further, it is possible to prevent the air within the totally enclosed type driving electric motor from being heated, whereby the temperature of the bearing is increased.
Accordingly, it is possible to improve a cooling performance of the bearing portion and it is possible to restrict a temperature increase of the totally enclosed type driving electric motor. In particular, it is possible to prevent the lubricating grease from being prematurely deteriorated so as to extend an operational period, and it is possible to provide an effective structure of the bearing portion in the totally enclosed type driving electric motor that can reduce maintenance.
As mentioned above, since the fan is connected to at east one of the collar and the pressing plate, it is possible to generate the cooling wind due to the rotation of the fan, and it is possible to radiate the heat from the fan, so that it is possible to realize a further effective cooling operation of the totally enclosed type driving electric motor.
A sixteenth aspect is a totally enclosed type driving electric motor of the same type as that of the fifteenth aspect. In this sixteenth aspect, the fan generates a wind by rotating in accordance with the rotation of the pressing plate, and the wind cools at least one of said another end of the frame and the housing.
A seventeenth aspect is a totally enclosed type driving electric motor of the same type as that of the fifteenth aspect. In this seventeenth aspect, a cooling fin is connected to a part of at least one of said another end of the frame and the housing that receives the wind.
As mentioned above, a further effective cooling operation of the totally enclosed type driving electric motor can be realized by providing the fin in the portion receiving the wind.
In this case, the first to seventeenth aspects mentioned above can be freely combined with each other so as to be applied. For example, it is possible to apply to the totally enclosed type driving electric motor by combining the cooling space in accordance with the first aspect mentioned above with the fan in accordance with the eleventh aspect mentioned above.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities end combinations particularly pointed out hereinafter.